Such bipolar clamps are known, for example, from the PCT applications WO99/23933 and WO99/23959. They consist substantially of two clamp members joined together mechanically by means of an insulating screw or similar pivot joint, about which they can rotate with respect to one another, but are electrically insulated from one another. At the distal ends of the clamp members are provided electrode components for grasping tissue and conducting an electrical current through the tissue to cause coagulation. For manipulation of the bipolar clamp, the clamp members comprise handle devices at their proximal ends. The coagulation current is supplied by way of current-supply terminals at the proximal end of at least one clamp member. So that the bipolar clamp can be locked in a closed position, interlocking ratchets are disposed between the pivot joint and the proximal ends of the clamp members. This measure ensures that when the clamp is in the closed position, it holds the tissue securely.
However, the bipolar clamp disclosed in WO99/23933 presents two disadvantages.
First, the current supply is provided at only one clamp member; more precisely, from a terminal attached to the handle device disposed at the proximal end of the clamp member the current is supplied by two wires that follow a common route approximately as far as the pivot joint between the two clamp members. From that point on, the wires run separately to the electrodes to which they are electrically connected. Although this makes manipulation of the clamp easier, the arrangement of the wires in particular near the joint connecting the clamp members makes them vulnerable to wear and tear, especially when the clamp is frequently used; a fracture can appear in the electrical leads. Because of the severe mechanical loading of this kind of clamp, such an event is highly likely.
Furthermore, it is possible for a coagulation current to flow even before the clamp members have been locked in the closed position, because the time when current flows is determined by the operator. Therefore the operator must essentially perform three manipulations to coagulate tissue: grasping the tissue, locking the clamp members together and activating the current flow. This complicates the operation. The main problem is that the operator can easily activate the current by accident before the locking is completed, inducing an unintended coagulation.